【springboot系列】springboot+JSR303+全局异常处理

springboot+JSR303

前言

每次校验都要写一堆判空语句，判断字段长度，例如下面的代码，是否觉得很多余、很繁琐？

JSR303校验将你从垃圾代码中解放出来。

正文

一、引入依赖

    
    <dependency>
      <groupId>org.springframework.bootgroupId>
      <artifactId>spring-boot-starter-validationartifactId>
    dependency>

二、在Controller的入参处加上@Valid关键字

@Controller
@RequestMapping("/login")
public class LoginController {
    Logger logger = LoggerFactory.getLogger(LoginController.class);
    @Autowired
    private UserInfoSerivice userInfoSerivice;
    @RequestMapping(value = "/doLogin", method = RequestMethod.POST)
    @ResponseBody
    public Result<LoginUser> login(@Valid @RequestBody LoginUser loginUser){
        logger.info("loginUser:"+loginUser.toString());
        LoginUser result = userInfoSerivice.getByUsername(loginUser.getUsername());
        if (result==null){
            return Result.error(CodeMsg.MOBILE_NOT_EXIST);
        }
        if (MD5Util.formPassToDBPass(loginUser.getPassword(),loginUser.getSalt()).equals(result.getPassword())){
            return Result.success(result);
        }else {
            return Result.error(CodeMsg.PASSWORD_ERROR);
        }
    }
}

三、给参数对象添加需要的注解：

package xyz.haibofaith.miaosha.model;

import org.hibernate.validator.constraints.Length;
import xyz.haibofaith.miaosha.validator.IsMobile;

import javax.validation.constraints.NotNull;

/**
 * @author:haibo.xiong
 * @date:2019/5/14
 * @description:
 */
public class LoginUser {
    private Integer id;
    @NotNull
    @IsMobile(required = true)
    private String username;
    @NotNull
    private String password;
    @NotNull
    private String salt;

    public String getSalt() {
        return salt;
    }

    public void setSalt(String salt) {
        this.salt = salt;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "LoginUser{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", salt='" + salt + '\'' +
                '}';
    }
}

四、实现自定义注解IsMoible

实现当手机号为空或者手机号位数不是11位的时候直接报错。不进行数据库校验。
1、仿造NotNull注解写

@Target({ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.PARAMETER, ElementType.TYPE_USE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Constraint(
        validatedBy = {IsMobileValidator.class}
)
public @interface IsMobile {

    boolean required() default true;

    String message() default "手机号码格式错误";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};
}

2、实现校验类：

public class IsMobileValidator implements ConstraintValidator<IsMobile,String>{
    private boolean required = false;
    @Override
    public void initialize(IsMobile constraintAnnotation) {
        required = constraintAnnotation.required();
    }

    @Override
    public boolean isValid(String s, ConstraintValidatorContext constraintValidatorContext) {
        if (required){
            //必须
            return ValidatorUtil.isMobile(s);
        }else {
            //非必须
            if (StringUtils.isEmpty(s)){
                return true;
            }else {
                return ValidatorUtil.isMobile(s);
            }
        }
    }
}

3、校验工具类（校验逻辑分离：方便管理）

public class ValidatorUtil {
    public static Boolean isMobile(String value){
        if (StringUtils.isEmpty(value)){
            return false;
        }
        if (value.length()!=11){
            return false;
        }
        return true;
    }
}

五、后端对错误进行统一处理：

前面四步处理完后，后端系统已经可以区分前端传来的参数是否合规。但是，一旦校验不通过，会给前端一个非常不友好的提示，如下。

{"timestamp":"2019-05-16T08:08:31.062+0000","status":400,"error":"Bad Request",
"errors":[{"codes":["IsMobile.loginUser.username","IsMobile.username",
"IsMobile.java.lang.String","IsMobile"],
"arguments":[{"codes":["loginUser.username","username"],
"arguments":null,"defaultMessage":"username","code":"username"},true],
"defaultMessage":"手机号码格式错误","objectName":"loginUser","field":"username",
"rejectedValue":"185110686061","bindingFailure":false,"code":"IsMobile"}],
"message":"Validation failed for object='loginUser'. Error count: 1",
"path":"/login/doLogin"}

前端同学可能就会说，怎么返回错误提示不按照标准格式来呢？
此处则针对此种情况，对校验不通过的异常处理捕获并展示：
1、全局异常管理：

@ControllerAdvice
@ResponseBody
public class GlobleExceptionHandler {
    @ExceptionHandler(value = Exception.class)
    public Result<String> exceptionHandler(HttpServletRequest request,Exception e){
        if (e instanceof MethodArgumentNotValidException){
            MethodArgumentNotValidException ex = (MethodArgumentNotValidException) e;
            List<FieldError> fieldErrors = ex.getBindingResult().getFieldErrors();
            //多个错误，取第一个
            FieldError error = fieldErrors.get(0);
            String msg = error.getDefaultMessage();
            return Result.error(CodeMsg.BIND_ERROR.fillArgs(msg));
        }else {
            return Result.error(CodeMsg.SERVER_ERROR);
        }
    }
}

六、展示效果：

用户名超过11位

七、如何使代码更加优雅

请看下面的代码是否还有改进的余地：

LoginUser result = userInfoSerivice.getByUsername(loginUser.getUsername());
        if (result==null){
            return Result.error(CodeMsg.MOBILE_NOT_EXIST);
        }
        if (MD5Util.formPassToDBPass(loginUser.getPassword(),loginUser.getSalt()).equals(result.getPassword())){
            return Result.success(result);
        }else {
            return Result.error(CodeMsg.PASSWORD_ERROR);
        }

代码详解：对手机号不存在和密码错误的时候都是通过统一的返回格式塞入，然后返回到service层，然后从service层结果集----》controller层。
这么做其实已经比较优雅，但是如何更加优雅呢？用异常，有任何问题直接抛出自定义异常，然后通过五中异常处理去控制如何展示。
修改后的代码如下：

public Result<LoginUser> getByUsername(LoginUser loginUser){
        LoginUser result =userInfoDao.getByUsername(loginUser.getUsername());
        if (result==null){
            throw new GlobleException(CodeMsg.MOBILE_NOT_EXIST);
        }
        if (MD5Util.formPassToDBPass(loginUser.getPassword(),loginUser.getSalt()).equals(result.getPassword())){
            return Result.success(result);
        }else {
            throw new GlobleException(CodeMsg.PASSWORD_ERROR);
        }
    }

添加自定义异常：

public class GlobleException extends RuntimeException{
    private CodeMsg codeMsg;

    public GlobleException(CodeMsg codeMsg) {
        super(codeMsg.toString());
        this.codeMsg = codeMsg;
    }

    public CodeMsg getCodeMsg() {
        return codeMsg;
    }

    public void setCodeMsg(CodeMsg codeMsg) {
        this.codeMsg = codeMsg;
    }
}

在全局异常处理中添加如下代码：

@ControllerAdvice
@ResponseBody
public class GlobleExceptionHandler {
    @ExceptionHandler(value = Exception.class)
    public Result<String> exceptionHandler(HttpServletRequest request,Exception e){
        if (e instanceof GlobleException){
            GlobleException ex = (GlobleException) e;
            return Result.error(ex.getCodeMsg());
        }
        if (e instanceof MethodArgumentNotValidException){
            MethodArgumentNotValidException ex = (MethodArgumentNotValidException) e;
            List<FieldError> fieldErrors = ex.getBindingResult().getFieldErrors();
            //多个错误，取第一个
            FieldError error = fieldErrors.get(0);
            String msg = error.getDefaultMessage();
            return Result.error(CodeMsg.BIND_ERROR.fillArgs(msg));
        }else {
            return Result.error(CodeMsg.SERVER_ERROR);
        }
    }
}